The present invention relates to a cellular radio system which comprises: subscriber units, a base station comprising means for establishing a telecommunication connection to the subscriber units of the system, whereby a transmitter of the base station comprises means for supplying telecommunication signals to a community antenna system, and a receiver of the base station comprises means for receiving telecommunication signals transmitted from the community antenna system, and a repeater which comprises a connection unit for connecting the repeater to the community antenna system, and an antenna means for establishing a telecommunication connection to the subscriber unit by radio frequency signals, whereby the repeater is arranged to transmit telecommunication signals between the subscriber unit and the community antenna system. The invention further relates to a repeater for repeating telecommunication signals between a base station of a cellular radio system and a subscriber unit which repeater comprises: a connection unit which comprises means for connecting the repeater to a community antenna system having a signal transmission connection to the base station; an antenna means having a signal transmission connection to the subscriber unit on radio frequency signals; and signal processing means including a first signal processing branch for transferring the signals transmitted by the community antenna system to the radio frequency and for supplying the radio frequency signals via the antenna means to the subscriber unit, and a second signal processing branch for transferring the radio frequency signals received from the antenna means to a predetermined transmission frequency and for supplying transmission frequency signals further via the connection unit to the community antenna system. The invention also relates to a base station of a cellular radio system which comprises a transmitter arranged to transmit communication signals via a community antenna system to subscriber units, a receiver arranged to receive telecommunication signals transmitted via the community antenna system from the subscriber units.
This invention relates to cellular radio systems, such as the GSM system (Groupe Special Mobile), and especially to improving the audibility of cellular radio systems in places where the audibility of the base station is weak, such as inside buildings.
There are prior art solutions in which the aim has been to improve the audibility of the cellular radio system inside buildings by arranging a base station inside a building. In addition to its cost, the most significant weakness of this solution is that it is usually very difficult to place a single base station in such a place that its audibility to different parts of the building would be good. Therefore, in most cases the base station can be heard well only in certain parts of the building, for example, on some floors, whereas in other parts of the building the audibility of the base station is very weak. The high cost of this prior art solution is in part caused by the fact that the base station equipment is expensive, in addition to which, the installation of the cabling of the base station inside a building, for example, for establishing a transmission connection between the base station and the base station controller, can cause problems and can become expensive.